|Nebraska Department of Environmental Quality|
|Methane to Energy: |
Improving an Ancient Idea
At least as far back as the 10th century BC, methane gas captured from animal waste was used for heating bath water in Assyria. Through the years, additional energy sources have been developed to heat our water. But the use of methane gas captured from animal waste (biogas) continues, and is now occurring on a scale that the ancients could only have imagined. In Nebraska, with thousands of livestock operations, the potential use of manure for energy production and other value-added products is a natural extension of the operations and a possible new source of revenue.
The process that creates biogas is called anaerobic digestion. In its simplest form, an anaerobic digester biologically breaks down animal waste and captures the methane gas that is a natural by-product of the process. The biogas is then burned off or used for purposes such as fuel to power an engine that produces electricity and heat. The anaerobic digestion process also creates effluent. Effluent and the solid fiber derived from it can be converted into other products including liquid fertilizer for land application, compost, and bedding for animals. Other benefits include:
In the summer of 2001, the Department of Environmental Quality (DEQ) and the Nebraska Public Power District (NPPD) co-sponsored a roundtable discussion of biogas recovery from livestock operations, and the potential generation of energy. Thirty-six representatives from various organizations gathered to begin a collaborative exploration of possible benefits, obstacles, and issues related to biogas recovery in Nebraska.
The state’s methane energy potential has been estimated at approximately 4,500,000-kilowatt hours per day, or enough energy to power about 135,000 homes monthly.
Eighty-five percent of the estimated potential is from beef feedlot operations, twelve percent is from swine facilities, and the rest from chicken and turkey confinements. The challenge facing development of biogas recovery in Nebraska is that the portion of the industry with the largest potential — feedlot operations — is the most difficult to collect due to the size and basic logistics of these operations.
Use of biogas recovery in the United States has focused on placing anaerobic digestion facilities at individual confined animal feeding operations and dairies. In cases where the methane is converted into electricity, the electricity is often used to serve the operation’s own power needs. Any excess is typically sold to power companies.